Identification
The first two days are Black Marubozu days (open is the high of the day
and the close is the low of the day). The following day is a black day that
gaps in the same direction but trades up into the body of the second day.
The final day is a Black Marubozu that gaps up and sells off to engulf the
third day.

The Psychology
In a downtrend or within a pullback of an uptrend, the two consecutive
Black Marubozus indicate the bears are in complete control. The gap down
on the third candle is bearish and attempt #1 is made to rally the stock
(as evidenced by the upper shadow). Attempt #2 comes on the next day’s
gap up, but the stock sells off again to indicate the bulls are throwing
in the towel. But this is why the pattern works. Once the bulls are given
up, there are no more sellers, so the down trend stops. Once the shorts
start to cover, there are no sellers to stand in the way of a bounce.